Browsing by Author "Kan, CC"

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Coagulation monitoring in surface water treatment facilities
(1998)
Kan, CC
;
Huang, CP
;
環境工程研究所
;
Institute of Environmental Engineering
Coagulant dosing is traditionally determined according to results from jar-tests or operator's experience, which often lead to overdosing or-insufficient dosing. In this study, the feasibility of applying an optical monitoring technique to determine chemical dosage and to monitor the coagulation performance in water treatment plants were assessed. To examine the applicability of the monitor under various operation conditions, series of batch trials in the field were conducted to explore the effects of turbidity, pH and rapid mixing intensity on the effectiveness of coagulation. The performance was directly reflected in the output ratio of the monitor, which proved to be an effective index for the flee size and its settling velocity. Therefore, we consider that the optical monitor is an useful instrument in monitoring coagulation in water treatment. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.
Coagulation of high turbidity water: the effects of rapid mixing
(2002-03-01)
Kan, CC
;
Huang, CP
;
Pan, JR
;
環境工程研究所
;
Institute of Environmental Engineering
High turbidity water during the rainy season has long been a challenge to the waterworks in Taiwan. Coagulation is the critical process for solving this problem; however the dispersion of coagulants in, the concentrated solid phase is very difficult. in this study, the effects of rapid mixing on the PACI coagulation of high turbidity water were investigated in terms of turbidity and particle count. operational parameters of coagulant dosage, coagulant concentration and mixing intensity in the rapid-mixing step exhibited great impacts on the residual turbidity and particle count of the simulated system. Aggregation degree, as evaluated by the Photometric Dispersion Analyser (PDA), was influenced by the intensity of rapid mixing. Poor rapid mixing failed to induce aggregation to effectively coagulate the small and hard to settle particles.
Time requirement for rapid-mixing in coagulation
(2002-04-25)
Kan, CC
;
Huang, CP
;
Pan, JRS
;
環境工程研究所
;
Institute of Environmental Engineering
Mechanisms of coagulation have been widely investigated by many researchers. Little is understood about the critical role of rapid-mixing in water treatment. In this study, a photometric dispersion analyzer (PDA) was employed to monitor clay coagulation by alum and polymeric aluminum chloride (PACl). The effect of rapid-mixing time on particle removal was studied. A standard jar test was performed to determine the degree of destabilization of particles. Maximum ratio outputs of PDA measurements were inversely related to residual turbidities. Adequate rapid-mixing times evaluated from both PDA and mixing tests were close to each other. Studies of coagulation mechanisms at various rapid-mixing times indicated that mixing time had significant impact on charge neutralization and sweep coagulation. The difference in residual turbidity can be attributed to the characteristics of microflocs. The rise in residual turbidity in sweep coagulation suggested the breakage of microflocs. (C) 2002 Elsevier Science B.V. All rights reserved.